Youthful
by RuaBean
Summary: Where Hanji somehow gets Levi to test out one of their experiments and it goes right. Sort of. Except, instead of simply giving the captain youth-like energy like the drink is supposed to do, it literally makes him a youth again. A 6 year old youth.
1. Chapter 1

Hanji couldn't help but come up with experiments even when a certain titan was on his day off.

An oddly terrifying gleam reflected off of Hanji's glasses as they stared at Levi in anticipation. Somehow they had lured the captain into their lab before cornering him in an attempt to get him to be tested. Of course, they didn't tell the captain what it was until the two of them arrived at the lab.

"I have figured out a solution to the soldier's sleeping issues! This liquid has the ability to give you the energy you don't obtain from too much lack of sleep! It'll be a life saver for many soldiers on expeditions."

One of Levi's eyes almost twitched in annoyance at the other's excitement. He should've seen this coming when Hanji suspiciously asked for his help. He stood his ground even while they crowded his space, "And why do you need me for this experiment? Go pick on one of the new brats."

Hanji raised a finger in front of his face, grinning even more. "Ah, but you'd be the best person for this! Since your eye bags make you look like you haven't slept for more than a few hours in your life, it would be obvious to see the change," they laughed, unaware that Levi was most definitely giving them a glare that could kill Titans. They just continued, "It will make you feel youthful! What could be wrong with that?"

By now, Hanji had placed both hands to the wall on each side of Levi, successfully blocking him from leaving. Honestly, he could've tried ducking out of the position, but something in Hanji's eyes told him that they would do whatever it took to experiment on him. He didn't want to be tackled to the disgusting floor by them just from trying to leave. He sighed as he weighed his options, slowly losing hope that there was a good way out of this.

When Hanji's face got way too close for comfort while waiting for an answer, he shoved them back and spat out, "Fine, but just a little bit. Don't think I'll be your guinea pig all day. I have real work to do, you know." He couldn't tell if he had just signed himself up for an early death when Hanji practically squealed in delight and jumped, clapping at their success. He was just glad they moved away. Hanji most likely hadn't showered in days, too busy working on their questionable experiments for Eren. He could smell it. Not like he could get Hanji to clean more often. He'd tried that already.

"Okay, so go to that bed over there and sit down while I get the mixture," Hanji said, waving over at the cot by the corner as they practically bounded over to their experiment tables. Levi did as they said, just hoping that this would end quickly… and positively.

He looked down at the messy cot in disgust, noticing how the covers were disheveled. Eren had probably been there for some experiment the other day. He'd probably been on it for many days without the sheets being washed, actually. He obviously distrusted Hanji's idea of cleanliness with a passion. Levi decided to push the top covers all the way to the edge and had just sat down when Hanji suddenly appeared in front of him, a cup in hand with seemed to be a tea bag floating in the drink.

"What? Did you find out that tea is what's going to be our savior?" he asked dryly, taking the cup and looking into it.

Hanji blinked at him owlishly for a moment before bursting into a roar of laughter, "Hahaha! And people don't think you have a sense of humor!"

Levi couldn't help but groan at her in his rising annoyance.

"That bag just holds the ingredients that can't be mixed until they're used. When you add it to the liquid here, it starts the reaction between the ingredients to activate the solution!" Hanji stated, as if it would be fascinating to Levi. It wasn't.

"Okay, so I just drink this and, what, wait to feel different?" Levi replied, blowing on the hot drink. At least he could pretend it was something normal like tea. That made it easier to even think about drinking whatever it was in this situation.

"Basically!" Hanji said gleefully, watching intensely as they waited for Levi to take a sip. As if the effect would be immediate or something.

Levi rolled his eyes at the crazy commander. They really needed a new hobby outside of experimenting and Titans. Not that he could say anything. He blew a few more times in the cup, making sure he wouldn't burn off his tongue in the process, then finally took a tentative sip.

Hanji seemed to move closer, like would make the view more interesting in some way. "Go on. You can't get the full effect from just one sip."

Levi looked back up at them and glared, "Don't rush me, I'm just testing the temperature, Four-Eyes." He wouldn't admit to them, but it didn't taste half bad. He started taking bigger sips, finally making a dent in the drink. "So, how did you test this out before me?" he asked in between two rather large sips. He wanted to finish this quickly so he could leave the uncomfortable stare that belonged to Hanji.

"Oh, I've had about six rats drink it. So far, they've all reacted very well!" Hanji stated, nodding seriously.

It couldn't be helped when Levi spat some of the drink out, not even feeling bad that he'd sprayed the other in the face. "On rats?! Just rats?! You've got to be shitting me, Four-Eyes." And there was his death glare sported on his face again.

Hanji stepped back, wiping their face before shrugging, "What? You're the first person who actually let me test you for this! You can't stop now, you've already finished most of it, anyway." Even when Levi was attempting to kill them with his gaze, they couldn't help but anticipate the end results of their subject.

"I will kill you slowly and painfully if this goes wrong," he said, gritting his teeth. Oh, he was searing with anger, but unfortunately they were right. He had downed almost the entire drink. He collected himself and sighed, regretfully putting the cup back to his lips and taking the last mouthful of liquid. Oh, Hanji was going to get some major payback in the near future.

They were either not aware of their own impending doom or didn't care, because they were grinning from ear to ear. He seriously wanted to punch it off Hanji's face. "So now wha— "

Levi was cut off by the door opening, an unknown soldier popping his head in. He almost looked frightened when he realized he had walked into some engagement between the two higher-ups, but he cleared his throat. "C-commander Hanji Zoe, Commander Erwin Smith would like to speak to you in his office."

Hanji turned and smiled to the soldier, waving him off. "Okay, I'll be there in a minute!" They turned toward Levi, who was looking at them like _'don't you fucking dare leave me here'_ , but of course they both knew it couldn't be helped. "I'll be back as soon as possible! You just stay right where you are, okay? Thank you so much for doing this!"

Levi just grumbled a "fuck you too," under his breath as he watched them disappear from the room, the silence suddenly pressing into him with an ominous feeling. Knowing fully well that he could have swallowed poison, personally made by a psychotic doctor, he couldn't help but fidget in his spot. It should only be a matter of time before the effects would become noticeable. Levi suddenly understood why that radical religious group prayed. He really hoped in this moment that whatever cosmos that was watching them was giving him some sort of good will. Honestly, he'd rather die by a titan than Hanji. Not that there was much difference, he joked blandly.

After a few minutes, Levi started to feel the effects, however, it was the opposite of what he was expecting. His eyebrows furrowed in concern. Why was he feeling unnaturally drowsy? Shouldn't he be more awake? Something was wrong. He had to go find Hanji.

Unfortunately, his body screamed otherwise and he was starting to think the crusty, old cot was becoming comfy. Really comfy, in fact. Maybe he should listen to Hanji and stay here. He could simply lie down and ride it out. This is exactly what he did, and soon after relaxing against the covers, his eyes fluttered shut. Hanji could wake him up when they came back.


	2. Chapter 2

**Author's Notes:**

Hello everyone! Sorry, this is my first story I'm posting on fanfiction, so I'm still learning how everything works. Please be patient as I figure this out! Also, this is my first full-out story I've posted to public, so be kind. However! I always encourage critiques/comments/etc. If I missed any grammars, please let me know, as I am my only 'peer' review at the moment. Do I even count as a "peer" reviewer, if it's just me?

One more note. I should be posting each chapter at least weekly, if not earlier. If I'm excited enough to write, it should be posted earlier. Otherwise, check back weekly and I should have something new! Thank you so much for your interest in this and I hope you stay entertained!

The talk with Commander Erwin didn't take terribly long, he sure knew how to use his time efficiently. This was a good thing for Hanji because that meant they could head back to Levi sooner. The lab room was in the same direction that Erwin was headed, so they walked together. The taller of the two couldn't quite understand the scientist's eagerness to get to the lab so quickly. Hanji were dying to see if the experiment worked, but they didn't explain that in case Erwin would look down on using Levi as a lab rat.

Hanji burst through the doors almost comically, announcing their arrival in a loud, enthusiastic tone, "Your favorite person is back and ready to see the results!" When there was silence, they blinked and looked around the room. Erwin, not in a hurry to get to his next destination, paused behind them.

"Is there something the matter?" Erwin stated, his gaze moving from Hanji to the inside of the room, not sure what was the problem right then.

Hanji just walked into the room, looking in every direction like a madman, "My test subject is missing!"

Hanji briefly wondered if the captain had gotten so annoyed with waiting that he left. That could be bad, what if the mixture wasn't correct for his body? Even Hanji would admit that their experiments could go wrong; they didn't deny that fact. Hanji immediately started looking around the lab more thoroughly. Levi really wouldn't leave, would he?

The cot was very much bare, except for the pillow that lay half-hazard at one end. The blankets had fallen into a big bundle on the floor next to it, possibly when the captain had gotten up. Hanji walked over and pressed their hands into the cot, as if Levi would magically appear from the action. They stood up straight again and let their gaze go over the room once more. He had to be in here.

Erwin walked all the way into the room, clearing his throat to grab the scientist's attention. "And for whom are we looking, might I ask?"

Hanji kept their gaze on the surroundings as they replied with a quick, "Oh, just Captain Levi." It would be wise not to see whatever face the commander would give them in reaction. They'd accept punishment after they found the missing person.

"And why did you think it would be a good idea to test out one of the best captains here...?" Erwin questioned stoically.

Hanji waved their hand at Erwin, "How about we talk about the 'why' later and instead find said captain so we know he's safe." They just grinned at the commander, knowing that he would have to agree that finding Levi was top priority. After one more search throughout the fairly open, albeit messy, lab, Hanji turned back to Erwin. "Where would he have gone from here if he left?"

"It seems quite obvious that he has," Erwin corrected them then turned to look at the doorway, "Paperwork has been rising, he probably felt that he needed to work on that instead of sitting idly." Hanji smacked their hands together excitedly, "Yes! He was complaining that he had work to do as an excuse to get out of the experiment!" One disdaining look from Erwin cut them off from explaining further in detail what went on so far today.

Instead, Hanji headed to the door, opening it and making a beeline for Levi's office. Erwin followed suit right behind them and within a few minutes they opened the door to an empty office. "Eh?" Hanji let out a dumbfounded sound, walking in and checking in every hidden spot possible. "Where else would he go?" they asked, peeking over the desk at Erwin in their crouching position.

Erwin held his chin in a hand as he contemplated what the captain might otherwise decide to do. "He doesn't seem to eat often, but it might be worth a look…" he mused. Honestly, he was as clueless as Hanji on where Levi would've gone. So they headed off in their new destination, hoping they'd find him sooner rather than later. Hanji was starting to actually worry that some negative side effect would happen while they weren't around to fix it. They thought the captain had more common sense than to run off like this.

Meanwhile…

Levi groaned as he lay on a cold floor, a blanket thrown over him to block out the sunlight. 'Since when was it so bright?' he questioned, feeling his headache from earlier slowly start to disappear. He had woken up in a strange place with light flooding the room like… 'No,' he chastised himself. He couldn't be upstairs. Not all the way up there. He hadn't the money to pay the hefty taxes to visit there.

'Besides,' he nodded to himself, 'I wouldn't leave mommy alone.' Even if, somehow, he'd obtained enough money to go above ground, not even a miracle could have given them both enough to go together. Levi would not leave his mother's side. Not after all she's struggled through to keep him alive down here. He knew eventually that he'd get sickly just like everyone else if he stayed, but he wouldn't abandon her.

Unfortunately, he had other things to worry about. Like where he was at this very moment. It was definitely not a familiar room. Not that he'd had a chance to look around before getting a splitting headache thanks to the light coming from the windows. Levi practically dove at the blankets that were resting on the edge of the cot to shield himself from the light.

As soon as he'd decided to chance looking out from the blankets to figure out where he was, the sound of a door opening then made him freeze in place. He'd listened intently to the strangers that had entered, not trusting them enough to show himself. What made him even more distrusting was that he heard both his name and 'test subject' in the conversation. Levi most definitely wasn't going to be seen by these two.

After they had left, Levi kept still under the blanket for a while longer. Finally, he decided they were gone long enough that the room was safe… for now. He pushed the covers away from his head and squeezed his eyes shut when the brightness antagonized his eyes again. As Levi started to blink to try and get used to it, he pushed himself up to stand and wrapped the blanket around himself, almost like a cloak.

He had no idea what to do next. Mommy most definitely wasn't around, so he couldn't just stay with her. Would he be able to get back to her eventually? Suddenly, a wave of anxiety overwhelmed him. What if he was never going back to her? What was he supposed to do now?

Levi looked around himself, finding no more clue as to where he was still. He'd have to leave. Just a tightening of the blankets around him and he tentatively walked up to the only doors in the room. Levi pressed an ear against the door, straining to listen for any passersby, but it didn't sound like there was anyone nearby. After opening the door, he confirmed that theory. He breathed a sigh of relief then tried closing the door. Unfortunately, the latch was picking a fight with him and he gave up, leaving it cracked as he looked down each side of the hallway. There was so much light…

After what seemed like ages walking, or rather, sneaking around the hallways, he thought he found a larger doorway that held promise. Maybe this would be the door to lead him out of this maze of a building. With a bit of struggle to reach the doorknob, he had finally turned it when suddenly someone called out.

"Hey, child! What are you doing here?!"

Levi immediately let go of the door, staring at the stranger in surprise. The adult looked just as startled, so he used that to his advantage and fled. Never mind that it was probably in the same direction he'd gone before, he just needed to get away. It didn't even occur to him that he had no real reason to run. He just didn't want to get caught by anyone. He wanted to be home. So he ran harder as the man finally started running after him.

Hanji let out a dramatic sigh. This had all gone terribly wrong. The captain was nowhere to be found and it was Hanji's fault that this was such a problem. They dragged their feet back to the lab, where it had all started. Erwin had made more disapproving looks in this search than Hanji could count on her hands.

"Do you think he could be in any danger with this drug?" Erwin asked the scientist, holding back a sigh. When Hanji looked like they were going to protest the usage of the word 'drug', Erwin held his hand up. "The test. I need to know so I can decide whether or not to get together a search party."

Hanji sighed yet again. The commander had a point. If the test hadn't worked properly, Levi could be in trouble soon. If he wasn't already. "I suppose it would be safe if we-"

As soon as they'd started to recommend the search party, they were cut off by the sound of someone yelling. As well as footsteps running in their direction. Hanji and Erwin stopped their conversation to see what would come around the corner.

"Come back here! You shouldn't be all the way out here! I just need you to stop running!"

Hanji looked back to Erwin with a mixture of curiosity and confusion. "Who would be trespassing all the way over here?"

As soon as they had asked that, they turned back to the commotion just in time for a small body to smack right into her. The figure fell backwards on the ground in the crash, getting tangled in the blanket that only made them look smaller. "Eh?!"

Hanji's eyes widened as she looked at the face of this kid. The familiar face looked up at her surprised, but also with a sliver of anger, probably at having their escape impeded. "C-captain?!" As their eyes widened in the realization, Levi's did the same… but more out of fear. Erwin and the young soldier that had been running after Levi just stood still and stared at the other two in silence.

Just as Levi had been extremely still on the ground, he got up the next moment with an inhuman speed, scrambling to flee into the lab again. Hanji blinked and turned on their heels to follow the now miniature captain into the room. Erwin just motioned for the soldier not to follow as he left Hanji to deal with the odd situation.


	3. Chapter 3

Author's Notes:

Hello again everyone! This time it took me a bit longer to update, I hope I wasn't keeping anyone waiting too long. It's really exciting to see how many views this story is starting to get! (They're probably not a lot, but for my first story it feels like a lot 3). Thank you for everyone who's continued to read this and I hope you continue to enjoy! Again, comments and critiques are always welcome. From your writing bean, lots of hugs and love! And little Levi's~

* * *

Diving under the cot in the far corner seemed like a good idea. Well, until Levi realized he had cornered himself. He barely thought about all the times he'd lain on the dirty ground, that was the least important problem at the moment. Right now, his focus was on the stranger that had followed him into the room.

Levi scrambled closer to the wall, as far away as he could get when the adult kneeled on the ground. They wouldn't get him. He'd make sure of it. Sure enough, as soon as the other person reached for him under the cot, he gave a small angry screech and kicked them straight in the face.

"Ow ow ow!" The stranger quickly moved backwards to sit up next to the cot, holding their face. Even if they couldn't see Levi at the moment, he stuck his tongue out at them.

"Lebi, no need do do dat," the stranger chastised to him, leaning over so they could look at him again. They were holding their nose, making them sound ridiculous.

"Shut up, I'll kick you again if you try anything else!" Levi spat at them. He glared daggers, wishing it were enough to veer them away.

Unfortunately, it didn't work. "Don't be afraid Levi, I won't hurt you!" They finally had let go of their nose and had lain flat on the ground, watching him intently. Gross. Levi didn't have a choice for being on the ground but they did.

"Liar," he retorted simply. This person was a bad person. They tested people. That and there was the whole 'stranger, danger' issue.

Their face didn't look evil, though, when he thought about it. Just weird. Especially when they blinked at him owlishly as if confused.

"I'm not lying! I'm a friend. You can believe me," the other said, shaking their head purposefully.

Levi's eyes narrowed at them. He just wanted to get away. Why was he stuck here? "But you do tests on people. I heard you."

There was that dumbfounded face again. The stranger waved their hands, "Oh, no! I mean, I do. I do research, but my tests are good!" They nodded quickly, then continued, "I'm Zoe Hanji, a soldier in the Survey Corps. Have you heard of the Survey Corps before, Levi?"

Levi listened, still pressed against the wall. When he heard the corps, his eyes widened. He didn't know much except for the name… and that they were from upstairs.

"Liar."

The stranger, rather, Hanji (they had a name to go with that dumb face now), shook their head even more than last time. "No, no! I'm not lying! Look! My jacket has the emblem!" They moved one arm forward as much as possible and tapped the wings with a finger enthusiastically.

It looked legit, for all Levi knew. He looked between the wings on the jacket and Hanji's face a few times, not sure what to think now. Sure, he was still distrusting, but now he was less sure of his thoughts. Why was this Hanji person here and what were they doing with him?

"You won't remember me because the test didn't work right, but we do know each other! You've been with us for…ah, well, let's just say a while." Levi didn't understand what Hanji was going on about. He'd never seen them in his life.

He was starting to get cramped staying under the bed like this now. It still was a sketchy idea to trust this person, but he wouldn't be able to stand crouching under here much longer. He looked around, noting again that there was no way out. He still didn't know where home was, even if he did escape. Levi looked back to Hanji cautiously, "How do I know you're telling the truth?"

How they would prove that, he had no idea. It was the best thing he could come up with in the moment, though.

Hanji tilted their head then hummed in thought, trying to think of something good enough. After a moment, they nodded, "Your name is Levi-"

"I already know you know that," Levi cut them off.

They just chuckled, "I was going to add Ackerman." The boy frowned further at them but let them continue.

"Your mother's name is Kuchel. You have an uncle named Kenny. Your birthday is the 25th of December. You have blood type A…"

Levi blinked at them as they rambled on. They sure seemed to know a lot. He didn't even know his own blood type before now. Maybe they weren't lying. However, even if they did know each other, he still couldn't remember.

Hanji noticed Levi stop listening, so they stopped listing off items. After a moment, they reached out a hand, pausing when Levi jumped in his spot before moving it forward again. "Here, we can greet each other again, if that will help. I'm Hanji, nice to meet you! What's your name?"

His eyes went from Hanji's outstretched hand to their face and back to the hand. He obviously didn't like this situation. He didn't have much of a choice, though, did he?

Finally, Levi tentatively reached out to touch Hanji's hand, his body tense as he waited for something bad to happen. When all they did was close their hand lightly around his and shake, he visibly relaxed. They already knew each other's names from earlier, but somehow restating it felt official. "Levi," he mumbled, "Nice to meet you…"

Hanji smiled that goofy smile and let go. "So are you ready to get out from under the cot yet? It's gotta be cramped and gross down there I bet!"

"I guess…" Levi replied after a moment. He didn't move, still secretly frightened of moving from this safe spot, as much as he disliked its qualities. He watched as Hanji scooted back, then they motioned for him to come out. He took a deep breath, then slowly pushed himself out from underneath the cot.

Already, he felt better getting out of that small space and he sat up. When he looked up at Hanji, their hands were outstretched. "There we go, come here. Would you like a new blanket? Maybe a clean one?" they mentioned, grabbing his interest.

Without replying, he nodded, allowing the bigger person pick him up in order to set him on his feet. He wouldn't drop the blanket until he saw another one, even if this one was super dirty by now. It was like a shield, somehow. When Hanji grabbed his hand to lead him over to a cabinet, he let them pull him along.

Levi didn't catch Hanji's gleeful face when he'd accepted the hand, keeping his eyes to the floor. When they stopped, the cabinet was opened and Hanji's hand disappeared. He heard shuffling from above, then a grunt of approval.

"Switch with me, Levi," Hanji said as they kneeled down to his level, holding out a new blanket. Levi looked up then silently handed them the old one, grabbing the much fresher fabric. He'd only just unraveled the material when Hanji started helping him cover himself with this one, having already tossed the old one on a table to deal with later.

They made a cooing noise, ruffling his hair and he pushed their hand away. "Is that better?" He gave them a look of distaste at their gesture but nodded. They stood straight again then held their hand out once more for Levi.

This time he didn't even think twice before grabbing the outstretched hand, once more allowing them to lead him. "Would you like some food? It's about lunchtime, you're probably hungry."

Levi didn't want to take the chance of meeting other strangers, but he couldn't help but feel his stomach rumble in hunger. "Okay…"

They both headed to the doorway and exited the lab. When Levi looked up again, he faced a very tall, very powerful-looking man. His feet stopped in their tracks as he stared up at piercing blue eyes, a mixture of awe and fear striking him.

The man stared back with a look of interest and… he wasn't sure what else. He was too focused on not fleeing from the giant's gaze. So, he tightened his grip on Hanji's hand and moved closer to them. He'd decided it was okay to trust Hanji, even if only a little, so he waited silently to see how they acted toward the blonde man.

Hanji just squealed at him, clutching at their heart with their open hand and talked to the man excitedly, "Isn't he the most precious thing ever? This is so exciting! Come on, Erwin, you can't be angry looking at this, right?"

The man, Erwin, moved his gaze to Hanji, his expression becoming more unamused than anything. "I do not find this situation amusing in any way, Hanji. I expect you to fix the issue soon."

"Oh, stop being such a grump. It could've been worse! Anyway, the other test effects were all temporary. The only difference was how long it took for them to wear off," Hanji waved the man off. "You should enjoy this while it lasts!"

Erwin only sighed, looking back to the child and was quiet for a moment in his thoughts. Hanji poked at his chest, "You should introduce yourself. Don't be a scary brute!" Erwin almost looked like he was going to retort, but then stopped.

The large man then moved down to kneel in front of Levi, who unconsciously moved even closer to Hanji's leg, watching Erwin cautiously. He couldn't tell if the man was disapproving of Levi or what he thought. When the man gave a small smile and held out his hand, Levi let out a breath he didn't realize he'd been holding.

"Erwin Smith, nice to meet you Levi," the man said, his voice much softer than when he was bickering with Hanji.

Levi tentatively took his hand and nodded, "Nice to meet you." Erwin shook their hands slightly and let go, pulling the blanket tighter around the boy in a genuinely friendly gesture before pushing himself back up to stand.

"Levi is under your care while he's in this situation. All of your experiments are prohibited until everything is fixed."

Hanji opened their mouth to complain about their experiments, but he gave them a look that stopped them. "Keep me up to date. Now, I'll be on my way." With one more look to the child captain, Erwin turned and headed down the hallways.

After Erwin left, Hanji looked down and grinned at Levi, ruffling his hair even while he protested it. "I really can't complain about being on babysitting duty with such a cutie!"

"I'm not a baby," Levi retorted, his nose crinkling in his displeasure of the term. Hanji just laughed and tugged at his hand gently. "Alright, alright, my little man. Let's get some food!" They started walking and Levi followed, his cheeks puffing as he ignored the nicknames. He really did want food by now and that trumped his annoyance. He was so hungry he forgot about the confusing conversation before him.

Levi sped up, this time pulling Hanji even if he didn't know where he was going. "You're walking too slow," he mumbled as Hanji chuckled and matched the child's speed, telling him the directions when necessary so he could keep the lead.


End file.
